Seen together ~ Moon and Venus — neighbours only
to our eyes!
This evening, 14 September 2026, at Triplicane saw a slender crescent Moon appeared to almost embrace brilliant Venus in the western sky. They are separated by an enormous distance in space; yet, viewed from Earth, their orbital paths briefly brought them into the same small patch of our sky — a lovely celestial conjunction.
Venus
is one of the most fascinating planets because, in some ways, it is Earth’s
near-twin — and in other ways, it is almost the opposite of Earth. Venus is the second
planet from the Sun. It is almost the same size as Earth: its
diameter is about 12,100 km, only a little
smaller than Earth’s 12,742 km. It is a rocky planet with a metal-rich
interior, mantle and crust, and it probably formed around 4.5
billion years ago from the same rotating disc of gas, dust and
rocky material that produced the Sun and the other planets. In the early Solar
System, countless small rocky bodies collided and gradually accreted into
larger worlds; Venus was one of those worlds.
What
makes Venus especially interesting is what happened afterwards. It may once
have had far more water than it has today, perhaps even conditions much less
hostile than the present planet. But Venus is closer to the Sun, and over
immense periods its atmosphere became dominated by carbon
dioxide. This produced an extreme greenhouse effect. Today its
surface temperature is around 465°C — hot
enough to melt lead — and the atmospheric pressure at the surface is about 90
times that of Earth. Its clouds are largely made of
sulphuric-acid droplets.
Yet from Earth Venus looks serene and beautiful. Its thick
clouds reflect sunlight extremely efficiently, which is why it becomes the
brightest “star-like” object in our sky after the Sun and Moon. The “Evening
Star” you photographed is therefore actually a fiercely hot, cloud-covered
planet.
One extraordinary
fact about Venus is its rotation. It turns very
slowly and backwards compared with most planets. One rotation
takes about 243 Earth days, while Venus
goes around the Sun in about 225 Earth days.
So, remarkably, a Venusian day is longer than a Venusian year. It sounds strange because we use “day” and
“year” casually.
On
Venus:
- One
year
= the time Venus takes to go once around the Sun: about 225 Earth days.
- One
rotation day
= the time Venus takes to turn once on its own axis: about 243 Earth
days.
So
Venus completes an entire orbit around the Sun before it has finished one
full rotation on its axis. And because it rotates in the opposite
direction, the Sun would appear to rise in the west and set in the east.
There are two photos one taken with Nikon d7500 /
300mm lens and then cropped and another taken casually with Pixel Pro 8
phone. Venus, like the Moon, shows phases
— crescent, half, gibbous and nearly full — because it orbits closer to the Sun
than Earth does. Galileo’s observation of these phases in the early 1600s
became powerful evidence that Venus goes around the Sun rather than around
Earth.
If you wonder where are they :
The
Moon is much, much closer to Earth than Venus.
- Moon:
on average about 384,400 km from Earth. Its distance varies roughly
from 363,000 km to 405,000 km because its orbit is not perfectly
circular.
- Venus:
its distance from Earth changes enormously. At its closest it can be about
38 million km away; at the far side of the Sun it can be around 260
million km away.
So even when the Moon and
Venus look almost side-by-side in photograph, Venus is actually tens to
hundreds of times farther away. For
perspective, light takes only about 1.3 seconds to travel from the Moon
to Earth, whereas light from Venus can take roughly 2 to 15 minutes,
depending on where Venus is in its orbit.
For a casual observer the photo with Pixel may sound better but actually it is not – Nikon has given an astronomical picture. The processed Pixel picture has become a little more “illustrative” than what I actually saw. The original Pixel photograph is actually valuable precisely because it records the real Chennai rooftops, clouds and sky.
Nikon frame is the better astronomical
photograph because the Moon and Venus are cleaner, more delicate, and more
naturally rendered. The Pixel photograph is the better scene-setting
photograph because it shows the conjunction in the real urban night sky
above the rooftops. The clouds and buildings give it context and atmosphere.The
weakness of the Pixel image is that the phone’s night processing has made the
crescent rather bright and slightly bloomed, and Venus has become a small
starburst instead of a clean point. That
faint remainder of the Moon's globe is
visible inside the crescent in Pixel photo is earthshine — sunlight reflected
from Earth onto the Moon's night side and then reflected back to us.
One would be inclined to say ‘Moon
– Venus” conjunction over Chennai night sky – both much closer but that
apparent closeness is what astronomers call a conjunction.
They are emphatically not physically close: the Moon
is only a few hundred thousand kilometres from Earth, whereas Venus is many
tens or hundreds of millions of kilometres away depending on where it is in its
orbit. What is photographed and seen
here therefore is a beautiful perspective
alignment — rather like seeing two distant objects apparently
side-by-side although one is vastly farther away.
Interesting !
Regards – S Sampathkumar
14.9.2026
